Morpho-anatomical, physiological and biochemical responses of <i>Neltuma juliflora</i> to heavy metals under vehicular pollution

This study investigated heavy metals accumulation in <i>Neltuma juliflora</i> leaves, roots, and adjacent soils along a gradient of traffic intensity, and examined its morpho-physiological and biochemical responses to evaluate its suitability as a bioindicator and phytoremediator. Soil and plant samples were collected from low, moderate, high, and urban traffic zones within 0-500 m of roadways. Metal concentrations were markedly elevated in high-traffic areas. Washing the leaves significantly decreased surface metal deposition, notably Ni (59%), Cr (46%), and Cd (39%). Increased traffic density reduce stomatal and epidermal cell size, chlorophyll content, membrane stability index, while enhancing stomatal density, relative water content, ascorbic acid, and phenolic compounds. These results demonstrate the tolerance capacity of <i>N. juliflora</i> and support its use in monitoring and mitigating roadside heavy metal pollution.